Ugh, the problem with summaries is that they don't really explain the methodology thoroughly. If all it was was a questionnaire and bone length measurements with different breeds all lumped in together, then... it's a pretty poorly designed study.

Unless there is significant methodology they aren't putting in their summary, as far as I can tell there is no attempt whatsoever to identify, let alone control for, confounding factors (breed, size/bone length of relatives of the dogs in the study (if known), diet/nutrition, where the dog was acquired, how old the dog was when it was acquired, just to name a few). So as it stands, it's nothing more than a suggestion that further study is warranted IMO.

ETA: I actually truly, sincerely wish someone would do some well designed studies about this stuff. It's frustrating.